Ultraviolet exposure from indoor tanning devices: a systematic review.

Use of indoor tanning devices increases the risk of cutaneous melanoma and nonmelanoma skin cancer. Indoor tanning devices have become important sources of ultraviolet (UV) exposure, both UVB and UVA. This systematic review assessed UV measurements performed in indoor tanning devices related to irradiance level, wavelength distribution and similarities to natural sun. The study was performed in accordance with the MOOSE and PRISMA guidelines. We searched PubMed, Embase and Web of Science from inception to May 2015, and also examined the reference lists of the retrieved studies. Eighteen studies were included. Twelve studies examined the erythema-weighted UV irradiances of indoor tanning devices, 11 studies examined UVB and 13 studies studied UVA. Compliance with irradiance limits was reported in nine studies. Erythema-weighted irradiances were highest in the most recent studies. Most studies had mean values higher than from natural sun and with large variations between devices. All studies except two had mean unweighted UVB irradiances lower than from natural summer sun (at latitudes from 37°S to 35°N), while mean unweighted UVA irradiances were, with one exception, substantially higher than from natural sun. The high values of UVA exposure from modern tanning devices are alarming in light of the increased focus on UVA irradiance as a carcinogen, and as UVA exposure confers little protection against subsequent UV exposure.